Electric switch



' Feb. 20, 1940.

F. o. K UHN ELECTRIC SWITCH Filed Nov. 9, 1936 2 Sheets-Sheet 1 INVENTOR FRANK O. KUHN ATTORNEYS Feb. 20, 1940.. r'.- 5, KUHN 2,190,842

ELECTRIC SWITCH Filed Nov. 9, 1936 2 Sheets-Sheet 2 FIG.4.

FIG-.5.

INVENTOR FRANK 0. KUHN A TTORNEYS Patented Feb. 20, 1940 UNITED STATES PATENT OFFICE 4 Claims.

This invention relates generally to switches for controlling electric circuits and refers more particularly to improvements in switches embodying means for delaying opening the circuit 5 after the .switch control has been moved to its off position." I 7 It is one of the principal objects of this invention to improvegenerally switches embodyingv the above feature by simplifying .the construction of the several parts involved and by reducing the number of such parts to a minimum. In accordance with this invention, the construction of the switchis not only'materially simplified, but the operation thereof is rendered more efficient by reason of the extremely simple escapement mechanism provided to prevent disengagement of the relatively movable switch. contacts upon moving the switch control to its off position'and to permit the release of the contacts in predetermined'timed relation of movement of the switch control to its off position.

Another feature of this invention consists in the provision of an escapement mechanism for theabove purpose embodying a latch for positively holding the relatively movable'switch contacts into engagement and having pneumatically operated means effective upon movement of the switch control to its off position to release the contacts in predetermined timed relation to movement of the control to the latter position thereof.

Still another advantageous feature of this invention resides in the provision of escapement mechanism of the character set forth capable of being used in connection. with switches em bodying a well known and proven principle of operation. In addition, the invention contemplates a switch construction and esc'apement mechanism forming a unitary assembly compact in nature and capable of being readily installed.

A further object of the present invention consists in the provision of a switch construction embodying the above features which is effectively sealed against the entrance of dirt and moisture and which is durable in construction. This feature, as well as the above and other objects,-will be made more apparent as the description pro-- ceeds, especially when considered in connection with the accompanying drawings, wherein- Figure l is a central sectional view through the switch assembly and illustrating the several parts thereof in a position wh rein the switch control is in its off position and the circuit controlling means is latched by the escapement mechanism in the on position;

Figure 2 is a plan view of the construction shown in Figure l, with certain parts broken away for the sake of clearness;

Figure 3 is a sectional view taken'substantially on the plane indicated by the line 3-3 of Figure 2;

Figure 4 is a sectional view taken substantially on the plane indicated by the line 4-4 of Figure 2;

Figure 5 is a sectional view taken substantially on the line 5-5 of Figure 2 and illustrating the switch control in its on position;

Figure 6 is a cross sectional view taken on the line 6-6 of Figure 4;

Figure 7 is a fragmentary sectional view of a slightly modified form of the invention; and

Figure 8 is a fragmentary perspective view of the switch control means.

In the specific embodiment of the invention selected herein for the purpose of illustration, the invention is shown in connection with a switch operating on the well known toggle principle and comprising a casing l0 formed of molded rubber, Bakelite, or other suitable material and housing circuit controlling means ll adapted for actuation by a control member I2 pivotally supported on the casing ill for swinging movement in opposite directions. The circuit controlling means H comprises a pair of fixed contacts l3 respectively secured to the inner surfaces of the opposite side walls of the casing by means of the terminals l4 and having flexible fingers I5 extending inwardly from the lower ends thereof for frictional engagement with the cooperating movable contact member I 6. The movable contact member I6 is substantially U-shaped in elevation and is provided with laterally outwardly extending projections ll at the upper extremities of the leg portions thereof. The projections ll are positioned in suitable slots l9 formed in the opposite side walls of the casing to provide for swinging movement of the cross bar 20 of the U toward and away from the flexible fingers l5 of the cooperating fixed contacts l3. The distance between the fiexible fingers I5 is less than the width of the base portion of the U-shaped contact member 16 so that when the latter is swung to position the base portion thereof between the fingers, the latter are tensioned and frictionally engage the opposite sides of the U-shaped member to insure efiicient flow of electrical energy through the circuit.

"As briefly indicated above, the swinging contact member I6 is moved into and out of engagement with the fixed contact l3 by means of the end positioned on a projection 24 of the cross bar 20 and having the upper end secured to a lever, 25 permanently secured to the shaft 2|. ,.The axis of rocking movement of the switch contact I6 is so positioned with respect to the axis of rocking movement of the switch control shaft 2| that the line of action of the spring 23 alternately assumes positions on opposite sides of the contact member l6 when the control |2 is rocked from one extreme position to the other. In other words, the construction is such that when the,

control l2 isswung from the off position to the "on position, the upper end or the line of action of the spring moves from the'right-hand side (as viewed in Figure 1) of the axis of swinging movement-of the contact HS to the left-hand side of this axis ancfias a result, the contact member I6 is snapped into engagement with the cooperating fixed contacts l3. On the other hand, when the switch control 2 isswuing to its of! position, the line of action of the spring returns to the right-hand side of the axis of swinging movement of the contact l6 and tends to snap this contact out of engagement with the fixed contacts |5.

In the "present instance, provision is made herein for preventing swinging movement of the contact l6 out. of engagement with the relatively fixed contacts l5 when the switch control I2 is swung from the on position thereof to the off position of the same until a predetermined interval of time elapses. This is accomplished herein by escapement mechanism 26 embodying a latch 21 for holding the swinging contact |6 into engagement with the relatively fixed contacts |5 and having pneumatically operated means 28 for releasing the latch from the contact 6 in timed relation to swinging movement of the switch control from'its "on" to its oif position. In detail, the-latch 21 comprises an arm 29 pivotally supported within the casing on one side wall thereof and having a notch 30 in the swinging end thereof adapted to receive a projection 3|,extendingflatera1ly from the movable contact l6, when the latter is swung to its operative posithe projection and prevents disengagement of thecontact l6 with the contacts 3 by the spring 23 when the latter is moved to its off position by V the switch control I2.

The pneumatic means for releasing the latch arm 29 from engagement with the projection 3| in timed relation to movement of the switch control l2 from its on position to its .off position is shown in Figure 1 as having a sealedair chamber 33 formed by'the co-operation of a flexible diaphragm 34 with'a recess 35 in the inner side of a cap 36 removably secured to the rear end of the casing ID by means of the fastener elements, 31. The peripheral edges of the-diaphragm 34 are effectively clamped between the cap 36 and an annular sealing gasket 38 clamped against the underside of the casing l0 by the fastener elements 31. A pair of plates 39 are clamped to opposite sides of the central portion of the diaphragm 34 and these plates, as well as the diaphragm, are formed with aligned openingstherethrough for receiving a fixture 40. The fixture 40 is provided with a head portion 4| engaging the inner side of the innermost plate 39 and the lower end of the fixture is spun over the plate 39 at the outer side of the diaphragm to effectively clampthe latter therebetween. Upon reference to Figure 1, it will be noted that the central portion of the fixture is apertured, as at 42, to establish communication between the chamber 33 and atmosphere. An annular valve seat 43 is formed on the inner surface of the fixture 4| around the opening 42 and the latter is normally closed by a spring loaded valve disc 44 engaging the seat 43.

In the present instance, air is exhausted from the chamber 33 through the passage 42in the fixture 4| when the switch control I2 is moved from its off position to its on position. This pressure built up in the chamber 33 opens the valve 44, permitting the fluid or air in the chamber to escape into the atmosphere. On the other hand, when the cam 45 is moved by the control I2 to its off position, the spring 50 is free to act on the central portion of the diaphragm 34, tending to move the latter and projection 46 inwardly. The rate at which the spring moves the projection 46 inwardly is dependent upon the return of flow of the fluid or air back into the chamber 33 and this return fiow of fluid is controlled by a highly restricted vent 48 formed in the fixture 4| adjacent the passage 42. For the purpose of regulating the speed of travel of the projection 46, an adjustable valve member 43 is threaded in the restricted vent 48 and functions to vary the cross sectional area of this vent.

As the projection 46 approaches its in'wardmost position, the latch. arm 29 is released from the projection 3| on the contact member l6 and the spring 23 disengages the contact member l6 from the relatively fixed contacts l5 in the usual manner. For accomplishing this result, the projection 46 is provided with a shoulder 5| adapted, to engage a lateral projection 52 on the arm- 29 to lift the latter a sufficient distance to dis-- engage the free end of the same from the contact member l6."

It will benotedfrom Figure 2 of the drawings that the projection 46- operates in an extension 53 of the casing in and agasket 54 issecured in the extension for frictionally engaging the projection to provide a seal around the latter sufficient to prevent the entrance of dirt and moisture into the chamber of the casing containing the valves for the pneumatic means. As a result,-the switch will operate efiiciently over a longperiod of time and the cost of maintenance is reduced to the minimum.

tion, air is forcibly discharged from the chamber past the elastic check valve 62 by the projection 46 when the latter is moved outwardly by the switch control member and will be permitted to filter back into the chamber through the porous plug when the\cam on the switch control memher is in its released position. With the above exceptions, the modified construction operates in a manner identical to the embodiment previously described.

What I claim as my invention is:

1. In a device of the character described, a movable element, a movable operating member, resilient means interconnecting said member and element, whereby movement of said operating member tends to cause movement of said element, a latch engaging said element, an expansible sealed chamber, means normally biasing said chamber to expanded position, valve means for said chamber providing for timed expansion of said chamber under control of said biasing means, a part engaging said chamber and engageable by said member, the aforesaid movement of said member disengaging said member from said part to permit timed expansion of said chamber, and means on said part enga ins said latch to free same from said element.

2. In a device of the character described, a movable element, a movable operating member, resilient means interconnecting saidmember. and element, whereby movement of said operating member tends to cause movement of said element, a latch engaging said element, an expansible sealed chamber having a flexible wall, an aperture in said wall, anannular plate doubled around said aperture, means' normally biasing said chamber to expanded position, valve means for said chamber carried by said plate and providing for timed expansion of said chamber under control of said biasing means, a part engaging said chamber and engageable by said member,

the aforesaid movement of said member disengaging said member irom said part to permit timed expansion of said chamber, and means on said part engaging said latch to free same from said element.

3. In a device of the character described, an element movable to two positions, an operating member movable to two positions, resilient means interconnectingsaid member and element whereby movement of said member to one position biases said element to a corresponding position, a latch retaining said element in one position, an expansible chamber having a fixed and a movable wall, -a latch releasing part carried by said movable wall, means urging said wall in a direction to cause said latch releasing means to release said latch, said operating member operatively associated with said latch releasing part and eifective when said member is in position to bias said element toward latched position to move and retain said movable wall against its urging means, and effective when said operating member is in position to bias said element away from latched position to release said movable wall for motion by its urging means, a one-way valve in said chamber permitting ready movement of said movable wall against its urging means, and said chamber having an orifice controlling movement of said wall in the opposite direction.

4. In a device of the character described, an expansible chamber having a fixed and a movable wall, means urging said movable wall in one direction, a one-way valve adapted to be closed by the pressure difference caused by motion of said wall in said direction, said chamber having a metering orifice providing timed motion of said wall in said direction, a snap acting setting and releasing mechanism comprising a two position member, resilient means urging said member to either limiting position, a connection between said member and said movable wall adapted to move and retain said wall against its urging means when said member, is snapped to one position, and to release said wall for timed motion when said member is snapped to the other position.

FRANK O. KUHN. 

